1.\" Copyright (c) 1989, 1991, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" %sccs.include.redist.roff% 5.\" 6.\" @(#)vis.1 8.4 (Berkeley) 04/19/94 7.\" 8.Dd 9.Dt VIS 1 10.Os BSD 4.4 11.Sh NAME 12.Nm vis 13.Nd display non-printable characters in a visual format 14.Sh SYNOPSIS 15.Nm vis 16.Op Fl cbflnostw 17.Op Fl F Ar foldwidth 18.Op Ar file ... 19.Sh DESCRIPTION 20.Nm Vis 21is a filter for converting non-printable characters 22into a visual representation. It differs from 23.Ql cat -v 24in that 25the form is unique and invertible. By default, all non-graphic 26characters except space, tab, and newline are encoded. 27A detailed description of the 28various visual formats is given in 29.Xr vis 3 . 30.Pp 31The options are as follows: 32.Bl -tag -width Ds 33.It Fl b 34Turns off prepending of backslash before up-arrow control sequences 35and meta characters, and disables the doubling of backslashes. This 36produces output which is neither invertible or precise, but does 37represent a minimum of change to the input. It is similar to 38.Dq Li cat -v . 39.It Fl c 40Request a format which displays a small subset of the 41non-printable characters using C-style backslash sequences. 42.It Fl F 43Causes 44.Nm vis 45to fold output lines to foldwidth columns (default 80), like 46.Xr fold 1 , 47except 48that a hidden newline sequence is used, (which is removed 49when inverting the file back to its original form with 50.Xr unvis 1 ) . 51If the last character in the encoded file does not end in a newline, 52a hidden newline sequence is appended to the output. 53This makes 54the output usable with various editors and other utilities which 55typically don't work with partial lines. 56.It Fl f 57Same as 58.Fl F . 59.It Fl l 60Mark newlines with the visible sequence 61.Ql \e$ , 62followed by the newline. 63.It Fl n 64Turns off any encoding, except for the fact that backslashes are 65still doubled and hidden newline sequences inserted if 66.Fl f 67or 68.Fl F 69is selected. When combined with the 70.Fl f 71flag, 72.Nm vis 73becomes like 74an invertible version of the 75.Xr fold 1 76utility. That is, the output 77can be unfolded by running the output through 78.It Fl o 79Request a format which displays non-printable characters as 80an octal number, \eddd. 81.It Fl s 82Only characters considered unsafe to send to a terminal are encoded. 83This flag allows backspace, bell, and carriage return in addition 84to the default space, tab and newline. 85.Xr unvis 1 . 86.It Fl t 87Tabs are also encoded. 88.It Fl w 89White space (space-tab-newline) is also encoded. 90.El 91.Sh SEE ALSO 92.Xr unvis 1 , 93.Xr vis 3 94.Sh HISTORY 95The 96.Nm 97command appears in 98.Bx 4.4 . 99